In a large saucepan, bring broth and water to a boil over high heat. Add pasta.

Return to a boil.

Reduce heat and simmer until pasta is cooked.

Add chopped spinach and cook about 5 more minutes until it is wilted and heated through.

In a small bowl whisk together milk and flour.

Stir into pasta mixture and cook until thickened.

Stir in cheese and continue to stir until it melts.